The invention relates in general to communications systems and, more particularly, to wireless communications systems for providing high data rate services to a plurality of subscribers within a given service area.
Satellite-based communications systems are proposed that will make high data rate/low delay information transfer widely available to the public. However, as presently planned, such satellite systems require an expensive satellite transceiver and directional antenna for each terrestrial user of the system. As can be appreciated, this requirement can make the acquisition of high data rate services prohibitively expensive for many consumers. To reduce consumer costs, and provide high rate data services, a Wireless Information Transfer System (WITS) has been proposed that provides a centralized Wireless Access Unit (WAU) that is capable of providing an interface between a high data rate communications platform and a plurality of terrestrial users (e.g., military, residential, business, retail, medical, university, and/or mobile users). The WAU provides means for communicating with each of the plurality of terrestrial users via high data rate terrestrial wireless links, in one or more native-mode digital channels. Thus, the terrestrial users only require relatively low cost, terrestrial wireless communications equipment as opposed to more expensive satellite transceivers/antennas.
As is apparent from the above description, a WITS-type system can require a significant amount of bandwidth to support high data rate communications among a plurality of terrestrial users. Allocation of useable spectrum is a function that is highly regulated by the government and generally requires an expensive government license to acquire. In addition, the useable spectrum, at least in the lower frequency ranges, is crowded and may not include an adequate amount of available contiguous spectrum to support the required terrestrial links. Another option is to raise the frequency of operation of the terrestrial links of the WITS-type system to portions of the spectrum that are not as densely populated. However, higher frequencies generally require higher priced equipment, thus increasing the costs to consumers. In addition, higher frequency systems generally have a significantly reduced range of transmission, are more sensitive to weather and terrain variables, and are more expensive to maintain.
Therefore, there is a need for a method and apparatus for providing efficient utilization of available spectrum in a centralized or distributed information transfer system, thereby reducing or eliminating the need for a large spectrum allocation or fixed frequencies of operation.